diff mbox series

[3/3] mm, slab, kasan: replace kasan_never_merge() with SLAB_NO_MERGE

Message ID 20240220-slab-cleanup-flags-v1-3-e657e373944a@suse.cz
State New
Headers
Series cleanup of SLAB_ flags |

Commit Message

Vlastimil Babka Feb. 20, 2024, 4:58 p.m. UTC 
  The SLAB_KASAN flag prevents merging of caches in some configurations,
which is handled in a rather complicated way via kasan_never_merge().
Since we now have a generic SLAB_NO_MERGE flag, we can instead use it
for KASAN caches in addition to SLAB_KASAN in those configurations,
and simplify the SLAB_NEVER_MERGE handling.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 include/linux/kasan.h |  6 ------
 mm/kasan/generic.c    | 16 ++++------------
 mm/slab_common.c      |  2 +-
 3 files changed, 5 insertions(+), 19 deletions(-)

Comments

Xiongwei Song Feb. 21, 2024, 2:25 a.m. UTC | #1 
> The SLAB_KASAN flag prevents merging of caches in some configurations,
> which is handled in a rather complicated way via kasan_never_merge().
> Since we now have a generic SLAB_NO_MERGE flag, we can instead use it
> for KASAN caches in addition to SLAB_KASAN in those configurations,
> and simplify the SLAB_NEVER_MERGE handling.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Ran a rough test with build and bootup with CONFIG_KASAN_GENERIC enabled,
feel free to add

Tested-by: Xiongwei Song <xiongwei.song@windriver.com>

Thanks,
Xiongwei

> ---
>  include/linux/kasan.h |  6 ------
>  mm/kasan/generic.c    | 16 ++++------------
>  mm/slab_common.c      |  2 +-
>  3 files changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index dbb06d789e74..70d6a8f6e25d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -429,7 +429,6 @@ struct kasan_cache {
>  };
> 
>  size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object);
> -slab_flags_t kasan_never_merge(void);
>  void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>                         slab_flags_t *flags);
> 
> @@ -446,11 +445,6 @@ static inline size_t kasan_metadata_size(struct kmem_cache
> *cache,
>  {
>         return 0;
>  }
> -/* And thus nothing prevents cache merging. */
> -static inline slab_flags_t kasan_never_merge(void)
> -{
> -       return 0;
> -}
>  /* And no cache-related metadata initialization is required. */
>  static inline void kasan_cache_create(struct kmem_cache *cache,
>                                       unsigned int *size,
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index df6627f62402..d8b78d273b9f 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -334,14 +334,6 @@ DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
> 
> -/* Only allow cache merging when no per-object metadata is present. */
> -slab_flags_t kasan_never_merge(void)
> -{
> -       if (!kasan_requires_meta())
> -               return 0;
> -       return SLAB_KASAN;
> -}
> -
>  /*
>   * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
>   * For larger allocations larger redzones are used.
> @@ -372,13 +364,13 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned
> int *size,
>         /*
>          * SLAB_KASAN is used to mark caches that are sanitized by KASAN
>          * and that thus have per-object metadata.
> -        * Currently this flag is used in two places:
> +        * Currently this flag is used in one place:
>          * 1. In slab_ksize() to account for per-object metadata when
>          *    calculating the size of the accessible memory within the object.
> -        * 2. In slab_common.c via kasan_never_merge() to prevent merging of
> -        *    caches with per-object metadata.
> +        * Additionally, we use SLAB_NO_MERGE to prevent merging of caches
> +        * with per-object metadata.
>          */
> -       *flags |= SLAB_KASAN;
> +       *flags |= SLAB_KASAN | SLAB_NO_MERGE;
> 
>         ok_size = *size;
> 
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 238293b1dbe1..7cfa2f1ce655 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -50,7 +50,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
>   */
>  #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
>                 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
> -               SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())
> +               SLAB_FAILSLAB | SLAB_NO_MERGE)
> 
>  #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
>                          SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
> 
> --
> 2.43.1
Chengming Zhou Feb. 21, 2024, 7:14 a.m. UTC | #2 
On 2024/2/21 00:58, Vlastimil Babka wrote:
> The SLAB_KASAN flag prevents merging of caches in some configurations,
> which is handled in a rather complicated way via kasan_never_merge().
> Since we now have a generic SLAB_NO_MERGE flag, we can instead use it
> for KASAN caches in addition to SLAB_KASAN in those configurations,
> and simplify the SLAB_NEVER_MERGE handling.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>

Thanks!

> ---
>  include/linux/kasan.h |  6 ------
>  mm/kasan/generic.c    | 16 ++++------------
>  mm/slab_common.c      |  2 +-
>  3 files changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index dbb06d789e74..70d6a8f6e25d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -429,7 +429,6 @@ struct kasan_cache {
>  };
>  
>  size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object);
> -slab_flags_t kasan_never_merge(void);
>  void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>  			slab_flags_t *flags);
>  
> @@ -446,11 +445,6 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache,
>  {
>  	return 0;
>  }
> -/* And thus nothing prevents cache merging. */
> -static inline slab_flags_t kasan_never_merge(void)
> -{
> -	return 0;
> -}
>  /* And no cache-related metadata initialization is required. */
>  static inline void kasan_cache_create(struct kmem_cache *cache,
>  				      unsigned int *size,
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index df6627f62402..d8b78d273b9f 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -334,14 +334,6 @@ DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
>  
> -/* Only allow cache merging when no per-object metadata is present. */
> -slab_flags_t kasan_never_merge(void)
> -{
> -	if (!kasan_requires_meta())
> -		return 0;
> -	return SLAB_KASAN;
> -}
> -
>  /*
>   * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
>   * For larger allocations larger redzones are used.
> @@ -372,13 +364,13 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>  	/*
>  	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN
>  	 * and that thus have per-object metadata.
> -	 * Currently this flag is used in two places:
> +	 * Currently this flag is used in one place:
>  	 * 1. In slab_ksize() to account for per-object metadata when
>  	 *    calculating the size of the accessible memory within the object.
> -	 * 2. In slab_common.c via kasan_never_merge() to prevent merging of
> -	 *    caches with per-object metadata.
> +	 * Additionally, we use SLAB_NO_MERGE to prevent merging of caches
> +	 * with per-object metadata.
>  	 */
> -	*flags |= SLAB_KASAN;
> +	*flags |= SLAB_KASAN | SLAB_NO_MERGE;
>  
>  	ok_size = *size;
>  
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 238293b1dbe1..7cfa2f1ce655 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -50,7 +50,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
>   */
>  #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
>  		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
> -		SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())
> +		SLAB_FAILSLAB | SLAB_NO_MERGE)
>  
>  #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
>  			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
>
Andrey Konovalov Feb. 21, 2024, 8:48 p.m. UTC | #3 
On Tue, Feb 20, 2024 at 5:58 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> The SLAB_KASAN flag prevents merging of caches in some configurations,
> which is handled in a rather complicated way via kasan_never_merge().
> Since we now have a generic SLAB_NO_MERGE flag, we can instead use it
> for KASAN caches in addition to SLAB_KASAN in those configurations,
> and simplify the SLAB_NEVER_MERGE handling.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>  include/linux/kasan.h |  6 ------
>  mm/kasan/generic.c    | 16 ++++------------
>  mm/slab_common.c      |  2 +-
>  3 files changed, 5 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index dbb06d789e74..70d6a8f6e25d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -429,7 +429,6 @@ struct kasan_cache {
>  };
>
>  size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object);
> -slab_flags_t kasan_never_merge(void);
>  void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>                         slab_flags_t *flags);
>
> @@ -446,11 +445,6 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache,
>  {
>         return 0;
>  }
> -/* And thus nothing prevents cache merging. */
> -static inline slab_flags_t kasan_never_merge(void)
> -{
> -       return 0;
> -}
>  /* And no cache-related metadata initialization is required. */
>  static inline void kasan_cache_create(struct kmem_cache *cache,
>                                       unsigned int *size,
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index df6627f62402..d8b78d273b9f 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -334,14 +334,6 @@ DEFINE_ASAN_SET_SHADOW(f3);
>  DEFINE_ASAN_SET_SHADOW(f5);
>  DEFINE_ASAN_SET_SHADOW(f8);
>
> -/* Only allow cache merging when no per-object metadata is present. */
> -slab_flags_t kasan_never_merge(void)
> -{
> -       if (!kasan_requires_meta())
> -               return 0;
> -       return SLAB_KASAN;
> -}
> -
>  /*
>   * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
>   * For larger allocations larger redzones are used.
> @@ -372,13 +364,13 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>         /*
>          * SLAB_KASAN is used to mark caches that are sanitized by KASAN
>          * and that thus have per-object metadata.
> -        * Currently this flag is used in two places:
> +        * Currently this flag is used in one place:
>          * 1. In slab_ksize() to account for per-object metadata when
>          *    calculating the size of the accessible memory within the object.
> -        * 2. In slab_common.c via kasan_never_merge() to prevent merging of
> -        *    caches with per-object metadata.

Let's reword this to:

SLAB_KASAN is used to mark caches that are sanitized by KASAN and that
thus have per-object metadata. Currently, this flag is used in
slab_ksize() to account for per-object metadata when calculating the
size of the accessible memory within the object.

> +        * Additionally, we use SLAB_NO_MERGE to prevent merging of caches
> +        * with per-object metadata.
>          */
> -       *flags |= SLAB_KASAN;
> +       *flags |= SLAB_KASAN | SLAB_NO_MERGE;
>
>         ok_size = *size;
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 238293b1dbe1..7cfa2f1ce655 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -50,7 +50,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
>   */
>  #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
>                 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
> -               SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())
> +               SLAB_FAILSLAB | SLAB_NO_MERGE)
>
>  #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
>                          SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
>
> --
> 2.43.1
>

Otherwise, looks good to me.

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>

Thanks!
diff mbox series

Patch

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index dbb06d789e74..70d6a8f6e25d 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -429,7 +429,6 @@  struct kasan_cache {
 };
 
 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object);
-slab_flags_t kasan_never_merge(void);
 void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 			slab_flags_t *flags);
 
@@ -446,11 +445,6 @@  static inline size_t kasan_metadata_size(struct kmem_cache *cache,
 {
 	return 0;
 }
-/* And thus nothing prevents cache merging. */
-static inline slab_flags_t kasan_never_merge(void)
-{
-	return 0;
-}
 /* And no cache-related metadata initialization is required. */
 static inline void kasan_cache_create(struct kmem_cache *cache,
 				      unsigned int *size,
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index df6627f62402..d8b78d273b9f 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -334,14 +334,6 @@  DEFINE_ASAN_SET_SHADOW(f3);
 DEFINE_ASAN_SET_SHADOW(f5);
 DEFINE_ASAN_SET_SHADOW(f8);
 
-/* Only allow cache merging when no per-object metadata is present. */
-slab_flags_t kasan_never_merge(void)
-{
-	if (!kasan_requires_meta())
-		return 0;
-	return SLAB_KASAN;
-}
-
 /*
  * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
  * For larger allocations larger redzones are used.
@@ -372,13 +364,13 @@  void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 	/*
 	 * SLAB_KASAN is used to mark caches that are sanitized by KASAN
 	 * and that thus have per-object metadata.
-	 * Currently this flag is used in two places:
+	 * Currently this flag is used in one place:
 	 * 1. In slab_ksize() to account for per-object metadata when
 	 *    calculating the size of the accessible memory within the object.
-	 * 2. In slab_common.c via kasan_never_merge() to prevent merging of
-	 *    caches with per-object metadata.
+	 * Additionally, we use SLAB_NO_MERGE to prevent merging of caches
+	 * with per-object metadata.
 	 */
-	*flags |= SLAB_KASAN;
+	*flags |= SLAB_KASAN | SLAB_NO_MERGE;
 
 	ok_size = *size;
 
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 238293b1dbe1..7cfa2f1ce655 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -50,7 +50,7 @@  static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
  */
 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
 		SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
-		SLAB_FAILSLAB | SLAB_NO_MERGE | kasan_never_merge())
+		SLAB_FAILSLAB | SLAB_NO_MERGE)
 
 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
 			 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)